Daily Protein Requirements
Q. How much protein do I need each day?
There is no one-size-fits-all answer to that question, andresearch on the topic is still emerging.
In the U.S.,adults get an average of 15 percent of their calories from protein; for aperson who requires a 2,000 calorie per day diet, that’s about 75 grams ofprotein. In healthy people, increasing protein intake to 20-25 percent ofcalories can reduce the risk of heart disease, if the extra protein replacesrefined carbohydrates, such as white bread, white rice, or sugary drinks.Higher protein diets can also be beneficial for weight loss, in conjunctionwith a reduced calorie diet, although long-term evidence of their effectivenessis wanting.
For people in good health, consuming 20-25 percent ofcalories from protein won’t harm the kidneys. For people with diabetes or earlystage kidney disease, however, the American Diabetes Association recommendslimiting protein intake to 0.8 to 1.0 grams of protein per kilogram of bodyweight (roughly 10% of energy intake), since this may help improve kidneyfunction; in later stage kidney disease, sticking to the 0.8 grams per kilogramminimum is advisable.Consult a doctor or aRegistered Dietitian for individualized protein recommendations.
Fish and Mercury
Q. Fish seems to be a good source of protein, but what do you think about the recent concerns of mercury toxicity?
Fish is a good option for a protein source since it is low in fat and high in omega-3 fatty acids. Research suggests that eating just 6 oz per week of fatty fish, such as salmon or sardines, may be enough to reduce the risk of dying from heart disease by 36 percent and reduce the overall risk of death by 17 percent. This makes fish perhaps one of the healthiest foods that you can eat.
Although there has been some recent concern about contaminants in fish such as mercury and PCBs, the evidence suggests that the proven health benefit of fish consumption is much greater than the potential for harm among individuals who consume fish 1-2 times per week. However, for women who are or may become pregnant, women who are nursing, and young children, mercury toxicity may be a concern for some types of fish.
It is best to eat a variety of fish. Women who are or may become pregnant, women who are nursing, and young children should avoid shark, swordfish, king mackerel and tilefish; instead, they should eat two serving a week of a variety of other fish and seafood, such as salmon, shrimp, chunk light tuna, or scallops. People who eat fish five or more times a week should also limit consumption of fish high in mercury.
Q. What is protein, and why do we need it?
Take away the water and about 75 percent of your weight is protein. This chemical family is found throughout the body. It’s in muscle, bone, skin, hair, and virtually every other body part or tissue. It makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood. At least 10,000 different proteins make you what you are and keep you that way.
Twenty or so basic building blocks, called amino acids, provide the raw material for all proteins. Following genetic instructions, the body strings together amino acids. Some genes call for short chains, others are blueprints for long chains that fold, origami-like, into intricate, three-dimensional structures.
Because the body doesn’t store amino acids, as it does fats or carbohydrates, it needs a daily supply of amino acids to make new protein.
The aim of the Harvard School of Public Health Nutrition Source is to provide timely information on diet and nutrition for clinicians, allied health professionals, and the public. The contents of this Web site are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Web site. The information does not mention brand names, nor does it endorse any particular products.